The present invention relates to a coating method and apparatus for a semiconductor process, and, in particular, to a method and apparatus for coating a target substrate, such as a semiconductor wafer or an LCD substrate, with a coating liquid, such as a photo-resist liquid or a developing liquid. The semiconductor process includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having, for example, wiring layers and electrodes to be connected to a semiconductor device on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
In a process of manufacturing a semiconductor device or an LCD, coating apparatuses are utilized in various steps. A representative one of them is a coating apparatus of a photo-resist liquid, employed in a coating and developing system of the photo-resist. The photo-resist liquid is applied onto a target layer to be pattern-etched, such as a semiconductor, insulating, or conductive layer on a semiconductor, so as to form a photo-resist film on the target layer. The photo-resist film is exposed to light through a predetermined mask and is developed so that the film is patterned to copy the mask. Then, the target layer is etched, using the patterned photo-resist film as a mask.
Jpn. Pat. Appln. KOKAI Publication Nos. 7-8879, 7-8880, 7-8034, 7-80385, and 7-80386, and Jpn. U.M. Appln. KOKAI Publication No. 7-31168 disclose a coating method of a certain type for applying a photo-resist liquid. In this coating method, a target substrate and a nozzle for delivering the photo-resist liquid in a band shape are moved relative to each other in a direction perpendicular to the band of the photo-resist liquid, so that the top surface of the target substrate is coated overall with the photo-resist liquid.
However, this method entails the following problems. First, since a solvent contained in the photo-resist liquid is evaporated while the liquid is applied onto the target substrate from its one end to the other, there is a difficulty in forming a thin film, and the necessary amount of the photo-resist liquid is relatively large. Further, as shown in FIG. 8, more photo-resist liquid is applied at the start and end points of the coating process, thereby bringing about a difficulty in forming a film having a uniform thickness. Furthermore, the surface of the target substrate occasionally has a bad wettability relative to the photo-resist, depending on the properties of the surface, thereby bringing about difficulties in forming a film having a uniform thickness and in performing a process with a small amount of the photo-resist liquid.
An object of the present invention, therefore, is to provide a coating method and apparatus for a semiconductor process, which can form a coating film having a uniform and thin thickness, and can decrease the necessary amount of a coating liquid.
According to a first aspect of the present invention, there is provided a coating method for a semiconductor process, of coating a target region of a substrate with a coating liquid, comprising:
a pre-coating step of coating the target region of the substrate with a solvent for the coating liquid, by supplying the solvent onto the target region from a solvent supply port while supporting the substrate by a support which supports the substrate substantially horizontal; and
a main coating step of coating the target region of the substrate with the coating liquid after the pre-coating step, by supplying the coating liquid onto the target region from a coating liquid supply port while moving the substrate supported by the support and the coating liquid supply port relative to each other in a first direction.
According to a second aspect of the present invention, there is provided a coating apparatus for a semiconductor process, for coating a target region of a substrate with a coating liquid, comprising:
a support for supporting the substrate substantially horizontal;
a solvent supply port for supplying a solvent for the coating liquid onto the target region of the substrate supported by the support;
a coating liquid supply port for supplying the coating liquid onto the target region of the substrate supported by the support; and
first sifting means for moving the substrate supported by the support and the coating liquid supply port relative to each other in a first direction.
In the present invention, a coating liquid is supplied after wettability of the surface of a target substrate is enhanced relative to the coating liquid, so that the coating liquid is not repelled even if its amount is small, thereby forming a coating film having a uniform and thin thickness. Further, since the coating liquid can be supplied in an optimum mixing ratio relative to a solvent when the coating film is formed, the necessary amount of the coating liquid to be used is decreased. Furthermore, since the solve and the coating liquid are brought into contact and mixed with each other, it is possible to cause the coating liquid to have a uniform viscosity and to prevent bubbles from being produced in the coating liquid.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.